The SE network has a "protected question" feature that is justified by saying "this question is protected to avoid 'me too', 'thanks' and similar responses.

It is perfectly understandable. It is especially understandable that posting questions of similar content is definitely not allowed.

But if I want to communicate with the community (including thankful posts), I think the meta is a right place to do so. I had similar posts several times before in Space.SE and there, it was perfectly fine.

So, am I allowed to thank something, or announce anything in meta in general? Or is discussion tag for different purposes?

Depends per meta I think. In general meta is the part of the site where users discuss the workings and policies of main. I'm not sure how thanking and announcing things fit in that description but if it doesn't get closed or down voted on that particular meta ...
– reneJun 15 '16 at 13:45

@rene starting with the fact that SO meta is full of (often network-wide) announcements, I assume it should be OK.
– Zoltán SchmidtJun 15 '16 at 13:50

You mean by SE staff? That is different I guess.
– reneJun 15 '16 at 13:52

I've always looked at it this way: Meta has its own rules, and every once in a while, it's okay to bend them. So is this according to meta rules? No. Is it against meta rules? Again no, since only bad things are against rules.
– MargarineJun 15 '16 at 18:42

2 Answers
2

There's no one answer to this... every site is different and what is allowed on their meta depends on the site. Clearly, on Space, this is fine, since your questions have been left to their own devices.

Similarly, on sites like Mathematics, I've seen "congratulations" topics where people can celebrate reaching rep levels or badges earned. But, even there, they consolidated all of the posts into one as having individual questions for every event seemed to get a bit much for them.

Most sites will allow major announcements like appointments of moderators... though that's admittedly very site related... Others have site "events" like "which is your favorite super hero" (recently on SFF)... or "vote for your favorite question/answer of the quarter" (run regularly on M&TV.

It's really up to the site and if your announcements start getting closed, consider thinking about whether they're actually as useful as you think they are.

As to your first example, that's not an announcement so much as it's a question about why you got lots of votes, so I don't really see how it applies to your question.

Here on MSE, a simple "thank you" announcement, like the one you linked to, is off topic and will be closed. There are rare exceptions like this one and that one, where we can thank a long time SE team member who leaves, but it's really rare.

On per site meta this might be on topic, this varies between each site and should be asked on any site you want to do that. (On its meta of coure. :))

Announcements from the team (Stack Exchange team) are always on topic, on any meta site. Don't think I really need to explain.